The present invention relates to a layer element containing at least one regularly arranged monomolecular layer of an amphiphilic molecule and one fullerene and to a process for the production of this layer element using the transfer method of Langmuir-Blodgett. This method is described e.g. in European Patent Application 0 432 619 and in U.S. Pat. No. 4,772,856.
It is already known that C.sub.60 -fullerene forms rigid films on water/air interfaces. It is not possible to transfer these films, as is customary in the Langmuir-Blodgett method, to a perpendicularly immersed substrate. It is likely that at least in part multilayers are formed on the water surface. The transfer characteristics of fullerene LB films is improved by mixing the fullerene with the amphiphilic compound icosanoic acid (Takayoshi Nakamura et al, Langmuir 1992, Vol. 8, No. 1). Unfortunately, according to in-house tests with omegatricosenoic acid, the amount of fullerene which can be incorporated in the monomolecular layer is limited to about 50% by weight, and the thermal stability of the films thus produced is low. Owing to their strongly delocalized electron systems, fullerenes exhibit nonlinear optical properties similar to those of conjugated polymers. They have high .chi.(3) values which makes them ideally suitable for apparatuses for optical frequency tripling. For fullerene-containing LB layers, this is true all the more, the higher the fullerene content. A certain thermal minimum stability of the layers is necessary if they are to be used more widely.
Accordingly, the object was to describe a process which allows the fullerene content in an LB layer to increase and the thermal stability of such layer systems to improve.